Brassinosteroids signaling via BZR1 down-regulates expression of to control growth of seedlings.

expression and RT-PCR analysis revealed that is predominantly expressed in shoots of Arabidopsis seedlings under light conditions. -overexpressed mutant produced more ethylene relative to the wild-type, which resulted in reduced growth of Arabidopsis seedlings. The abnormal growth of seedlings recurred after the application of Co ions, suggesting that is a functional necessary to regulate the growth and development of Arabidopsis seedlings. Exogenously-applied brassinosteroids (BRs) inhibited the expression of , and an enhanced expression was found in , a BR-deficient mutant. Additionally, expression of was decreased in (a -dominant mutant), implying that BR signaling negatively regulates expression via in Arabidopsis. In the intergenic region of , four E-boxes and a BR regulatory element (BRRE) are found. Electrophoretic mobility shift and chromatin immunoprecipitation assays showed that BZR1 binds directly to the BRRE in the putative promoter region of . By binding of BZR1 to BRRE, less ethylene was produced, which seems to regulate the growth and development of Arabidopsis seedlings.